User manual

System Hardware Description 2–3
2.2.2 Single Modular Input /Output/Power Port
The interface port is an 8–pin female modular connector used for attaching the
Asynchronous Serial Communications Interface Cable. Allows triggering capability (at
pin 2) for an external triggering device, such as an object sensor or a switch. Power and
ground connections are also on this port.
2.2.3 Audible Indicator
The beeper can be disabled by using a configuration command. Refer to Chapter 4 for
information on setting configuration commands. The beeper also sounds on power–up or
reconfiguration as an audible self–check of software configuration.
2.2.4 Mounting Inserts
Inserts are molded into the housing to retain mounting screws. Inserts are available for
metric (3.5) or SAE (#6–32) screws.
2.3 Operating Theory
Figure 2.3 presents a block diagram of the basic SCANTEAM 3700 Machine Mount
CCD operation.
The SCANTEAM 3700 Machine Mount CCD looks for data input from the scanning
circuitry, which includes the LED reflector (illuminates the bar code target), the CCD
sensor and imaging lens (focuses the scattered optical energy from the bar code symbol),
and the peak detectors and comparator (generates a digital representation of the bar code
symbol to send to the microprocessor). Refer to Appendix A, CCD Operation and Bar
Code Scanning, for a detailed explanation of 3700 scanning circuitry operation. When
the 3700 sees a trigger, a read cycle is started. The read cycle is completed when a bar
code is read or the read timeout expires.
Auxiliary Trigger
(Optional)
Peak Detectors
and Comparator
RS–232
Communications
LED Pulse Generator
CCD Sensor
Decode
LED Reflector
Second Scanner
Digital Input
(Optional)
Figure 2.3 Basic Scanner/Decoder Operation
Note: A trigger can be a hardware trigger, such as an object sensor, or a software command,
such as a serial trigger command or continuous read trigger mode command, from the
host. Refer to chapter 4 for description of serial trigger and trigger mode commands..
During a read cycle, the 3700 evaluates scanner data for a valid bar code symbol. If a
valid bar code symbol is seen, data is placed into the output queue where it may be
transmitted to the host through the RS–232 communications port. The 3700 can
optionally be configured to send a “No Read” message when a read cycle times out.